Preheat oven to 350 degrees.
Sift together flour, baking soda, baking powder, and salt in a medium sized bowl.
In the bowl of an electric mixer, cream butter.
Add in sugars and beat until light and fluffy.Add in peanut butter and mix until combined.Add in eggs, combining well after each egg. Add vanilla.Alternate with flour mixture and milk. Mix until well combined.
Spread mixture into a greased jelly roll pan (cookie sheet with a rim). Make sure the batter is spread evenly in the pan.
Bake for 18-20 minutes or until the edges are brown and a toothpick inserted in the middle comes out clean. You do not want to over bake or your bars will be too crunchy.
While the cookie base bakes, make your frosting. In the bowl of an electric mixer, with the whisk attachment, combine the peanut butter and powdered sugar on low.
Slowly add in milk. Turn the mixer to medium high and whip the frosting until light and fluffy. Add more milk if the frosting is not a spreadable consistency.
When the cookie base is cool, spread the frosting evenly over the pan.
Prepare the chocolate goodness by placing your chocolate chips in a heat proof mixing bowl.
Heat the cream and butter over medium heat until the mixture is simmering, not boiling.
When it is hot enough, pour the milk mixture over the chocolate chips and whisk until smooth.
Whisk in the powdered sugar and stir until smooth. Allow mixture to cool to room temperature.
When chocolate goodness has cooled to room temperature, pour over frosting and cookie base.
Allow the bars to set in the fridge for a few hours, preferably overnight.
Use a knife dipped in water to cut the bars.
Keep bars in an airtight container in the fridge to keep their freshness.